For the compensation of rotational speed fluctuations of the loom, a drive arrangement for a loom and a shedding machine is known from DE-U 200 21 049.1, wherein at least the main drive shaft of the loom has an additional rotating inertial mass or flywheel mass for the compensation of the rotational speed fluctuations. This additional inertial mass, however, has a negative effect on the acceleration process during the start-up of the loom. This is problematic for applications with high operating rotational speed, especially if the run-up for the loom is required “in one weft insertion” for ensuring the woven fabric quality, that is to say the dynamics already of the first reed beat-up must correspond to the dynamics of the following reed beat-ups. If an additional inertial mass must also be accelerated, this quickly increases the drive power that is to be installed, to a level that is no longer economically justifiable.
In other looms with electric motor direct drive, an inertial mass connected with the main drive shaft is omitted or avoided, in order not to delay or to make-difficult the acceleration process during the start-up of the loom. The avoidance or omission of an additional inertial mass, however, as already discussed above, leads to considerable rotational speed fluctuations per weaving cycle. For the compensation of the rotational speed fluctuations, it is obvious to influence the fluctuations in the rotational speed of the electric motor drive through corresponding controlling or regulating of the supply of electrical energy. Such influencing, however, leads to considerable loading of the drive train of the loom and of the shedding machine. Moreover, such a rotational speed compensation does not lead to an operating manner with energy constancy; the resistive or dissipative heat losses and loading for the motor and power electronics are very high.
It is further known from DE-U 200 21 049.1 to separate the loom and the shedding machine with respect to the drive technology, that is to say to allocate at least respectively one electric motor drive to the main drive shaft of the loom and to the drive shaft of the shedding machine. Associated therewith is the advantage that a rigid synchronization between loom and shedding machine is no longer present; at any time it is thus fundamentally possible to flexibly embody the tuning or adaptation of the operating behavior of loom and shedding machine corresponding to the weaving requirements, that is to say to select the synchronicity of both drive systems with respect to basic tuning or adaptation (for example shed closure at what loom position angle) and with respect to the permissible tolerances within broad limits. This embodiment of the drive synchronicity as desired within broad limits, however, in turn leads to considerable loading of the drive train of the loom and/or shedding machine; and similarly, due to the necessary control or regulating efforts, the resistive or dissipative heat losses and loading of the motor and the power electronics become very high. These disadvantages become still greater because the loading of the electric motor drive of the shedding machine is dependent on the motions of the shedding means (shafts; lifters), thus dependent on the weave pattern or generally dependent on the weaving application.
Now, due to the omission of the previous rigid coupling between loom and shedding machine, however, influences for the tuning or adaptation of the operating behavior of both machines become necessary in such a manner so that the so-called weft insertion window, with reference to the respective operating rotational speed, becomes as large as possible and/or reproduces itself as exactly as possible weft for weft in its time duration and/or development (that is to say how it opens or closes). This requirement arises very essentially in connection with gripper looms, wherein a gripper running character that is poorly tuned or adapted to the weft insertion window leads, for example, to the occurrence that the grippers do enter into the shed at the correct time point, but leave it too late. Thus, the gripper heads and/or the gripper rods rub on the warp threads of the shed that is already closing again. This can unduly heat the heads or rods, but also the warp threads. Moreover, this forced opening of the shed by the above mentioned gripper elements can produce defect locations in the woven fabric.